U.S. obesity trends and neighborhood effects

According to a study in The Journal of the American Medical Association (JAMA), in 2008 the obesity rate among adult Americans was estimated at 32.2% for men and 35.5% for women; these rates were roughly confirmed by the Centers for Disease Control and Prevention again for 2009-2010. Using different criteria, a Gallup survey found the rate was 26.1% for U.S. adults in 2011, up from 25.5% in 2008.

Though the rate for women held steady over the previous decade, the obesity rate for men continued to increase between 1999 and 2008, the JAMA study notes. Moreover, “The prevalence of obesity for adults aged 20 to 74 years increased by 7.9 percentage points for men and by 8.9 percentage points for women between 1976-1980 and 1988-1994, and subsequently by 7.1 percentage points for men and by 8.1 percentage points for women between 1988-1994 and 1999-2000.”

Though researchers have focused on a variety of factors that may affect obesity rates, the effect of community on individuals remains an area of continuing inquiry. A 2011 study in The New England Journal of Medicine, “Neighborhoods, Obesity and Diabetes: A Randomized Social Experiment,” examines data from a Department of Housing and Urban Development experiment with some 4,500 women and children from America’s poorer census tracts. Between 1994 and 1998, one group of those subjects was randomly assigned housing vouchers that were conditional on moving to lower-poverty (more affluent) neighborhoods; outcomes for this group were compared with those of other groups that had no such voucher conditions or did not receive vouchers at all. A follow-up survey was conducted between 2008 and 2010.

The study’s findings include:

For the group that moved to lower poverty neighborhoods, the overall rate of body-mass index scores of 35 or above (indicating obesity) was reduced on average by 4.61%.

In terms of raised glycated hemoglobin levels (6.5% or more is associated with an increased risk of diabetes), the group that moved to more affluent communities enjoyed a 4.31% reduction in the level of this indicator.

Within 10 years of the moving to a lower-poverty neighborhood with the voucher, the poverty rate of that group was reduced by 4.9%; the overall poverty rate in the other control groups was 33%.

The study’s authors conclude that the study’s findings “raise the possibility that clinical or public health interventions that ameliorate the effects of neighborhood environment on obesity and diabetes could generate substantial social benefits.”